One approach to creating a light source with a very high output power is to combine the individual output beams of a number of lower-power light sources such as lasers or light-emitting diodes. The combination of the individual output beams is accomplished spatially. That is, the individual output beams are supplied to a beam combiner, and the beam combiner directs the individual output beams in a parallel fashion through a small cross-sectional area to create the high-power beam. This approach also allows the individual lower-power light sources to be spaced apart to facilitate their cooling.
The existing beam combiners typically use spatial combiners having an optical surface whose properties are different in different areas. For example, the spatial combiners may include dielectric mirror stacks positioned on either side of a closely spaced masked region of high light transmission. One beam is reflected from the mirror stacks, while the other beam is passed through the region of high light transmission. The structure is repeated for each set of the light sources that is to be combined. This approach is operable to a degree, but has drawbacks. The structure of the spatial combiner is complicated and expensive to produce. There may be excessive heating of the beam combiners as the numerous lower-power light beams pass through them, reducing the life expectancy of the beam combiners before failure. In another approach, light beams may be combined with polarization combiners, which require polarization of the light beams and also are subject to excessive heating.
There is a need for a less-complex approach to spatially combining the output beams of a number of lower-power light sources such as laser or LED light sources. Any such approach should minimize heating of the apparatus to lengthen its expected lifetime. The present invention fulfills this need, and further provides related advantages.